Just one correction to the earlier post.
Efficiency = Heat input/ heat output
Heat input = mass flow rate times enthalpy difference of leaving air and entering air.
Heat output = mass flow rate times enthalpy difference of steam and condensate(presuming steam drying).
This gives the efficiency of the dryer with respect energy. If you want to check with respect to process, you should know the moisture content before and after drying. That is all.
Regards,
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